Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
  • F16K3/00—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing
  • F16K3/02—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing with flat sealing faces; Packings therefor
  • F16K3/16—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing with flat sealing faces; Packings therefor with special arrangements for separating the sealing faces or for pressing them together
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
  • F16K3/00—Gate valves or sliding valves, i.e. cut-off apparatus with closing members having a sliding movement along the seat for opening and closing
  • F16K3/30—Details
  • F16K3/34—Arrangements for modifying the way in which the rate of flow varies during the actuation of the valve
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
  • F16K5/00—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary
  • F16K5/08—Details
  • F16K5/12—Arrangements for modifying the way in which the rate of flow varies during the actuation of the valve
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
  • F16K51/00—Other details not peculiar to particular types of valves or cut-off apparatus
  • F16K51/02—Other details not peculiar to particular types of valves or cut-off apparatus specially adapted for high-vacuum installations

Definitions

• the invention relates to vacuum valves used to control the amount of negative pressure applied to a suction device in filtration operations, and particularly in papermaking machines.
• the invention particularly concerns a vacuum control valve that includes an adjustable aperture, such that the rate of change of its open area increases non-linearly in relation to the adjustment, while providing substantially linearly variable vacuum pressure.
• vacuum As used herein, the terms “vacuum”, “suction” and “negative pressure” have equivalent meanings and refer to an amount of air pressure developed in a confined space (e.g. piping, suction chamber, etc.) that is lower than ambient atmospheric air pressure.
• a confined space e.g. piping, suction chamber, etc.
• the invention is applicable to various types of filtration operation, but is particularly suitable for filtration in papermaking processes.
• the invention is described below primarily in relation to papermaking processes, it should be understood that the principles of the invention are not limited thereto, and can be applied to other filtration processes having similar requirements to papermaking processes.
• a very dilute slurry comprising about 1% papermaking solids in about 99% water (referred to as the "stock") is jetted at high speed and precision from a headbox onto an endless rotating belt called a forming fabric.
• the stock jet is aimed so that it lands on the forming fabric as the fabric passes in sliding contact over a forming element.
• Water from the stock drains through the forming fabric, leaving behind an embryonic mat of papermaking fibers and solids.
• the forming fabric and mat thereon pass over one or more drainage, agitation and suction devices which serve to both drain water and randomize the fiber distribution so as to provide a fibrous web.
• This web is transferred at the end of the forming section to a downstream press section where a further portion of the water is removed by mechanical means; the wet sheet is subsequently transferred to a dryer section of the papermaking machine where the remainder of the water in the web is removed by evaporative means.
• Controlled sources of vacuum are used in the forming and press sections of the papermaking machine to assist in removal of water from the web and to help control agitation of the stock. Due to the highly fluid nature of the stock in the forming section, precise control of the vacuum pressure applied to the forming fabric and embryonic web through the drainage and agitation devices is very important to the properties of the finished sheet. Other factors which raise the requirement for precise control in the press section of the papermaking machine are noted below.
• suction assisted drainage devices There are two general categories of suction assisted drainage devices presently used in papermaking processes: a) so-called low vacuum units, which supply from 0 to 60" (0 to 1500mm) of water vacuum to the forming fabric and web, and b) high vacuum units, which supply a higher vacuum level to the fabrics and web than low vacuum units. It has been found that valves presently in use in both of these types of suction assisted drainage devices do not provide acceptably consistent vacuum control outside the middle portion of their operating ranges.
• filtration resistance is well known in the papermaking arts (see e.g. Wildfong et al. "Filtration Mechanics of Sheet Forming. Part 1: Apparatus for Determination of Constant-Pressure Filtration Resistance” . J. Pulp Paper Sci., Vol. 26, No. 7 (July 2000), pp. 250-254). As the filtration resistance of the mat increases, the amount of applied vacuum must be adjusted correspondingly to maintain adequate drainage of the sheet.
• the present invention therefore addresses the problem of valve size and design selection for use in connection with a suction assisted drainage device, and is particularly directed at the unique operating conditions and environments in which these vacuum devices are located in papermaking processes.
• the present invention is particularly concerned with a valve apparatus which is used to control the amount of vacuum applied to the suction assisted drainage elements so that the applied vacuum varies linearly as the valve is opened or closed in response to adjustment from a very low to a very high level of vacuum pressure.
• the valve is designed to provide a non- linear continuously increasing rate of change in open area which provides a linear vacuum response that is directly proportional to the valve aperture position over up to at least about 90% of its operating range.
• valve aperture, or open area, of the valves of the invention allows for a linear change in the fluid flow rate (vacuum) in response to gradual linear adjustments of the valve from fully closed to fully open.
• This allows a single valve to be used for both high and low flow environments with more effective control of vacuum under both conditions. With a single valve for all positions in a papermaking vacuum system, changes in operating conditions do not require a change in valve size, thus significantly reducing the cost of spares.
• the valves of the invention provide a relatively linear change in the amount of vacuum pressure applied to the papermaking process in response to their adjustment; depending on the vacuum range being controlled, this change is directly proportional to the amount of open area provided to the vacuum source as the valve is opened or closed.
• the single valves of the invention can be provided as rotary sleeve type valves, in which the flow rate is regulated by adjusting the operational area of an aperture in the rotary sleeve presented to a valve body outlet, or can be provided as other types of movable valve, for example by providing the aperture in a movable member such that the operational area presented to the valve body outlet is adjusted by moving the member in a selected direction in relation to that outlet.
• valve aperture is configured such that in response to linear adjustment in the movable member of the valve to increase the open area, the rate of change of open area increases in a nonlinear manner, but provides a linear change in the flow rate through the aperture.
• the vacuum control aperture is shaped so as to provide a smooth, linear vacuum response to the amount of open area presented to the vacuum source and the amount of vacuum applied to the suction box through the valve.
• the invention therefore seeks to provide a valve for use in a vacuum drainage system, comprising
• valve body having (a) an exterior wall comprising an inlet operatively connectable to an output from a suction device, an outlet operatively connectable to a vacuum source, and
• a movable member movably secured within the interior chamber and comprising at least one movable member outlet aperture to selectively provide an operational open area constructed and arranged to allow fluid flow therethrough, and
• the at least one aperture has a configuration such that during movement of the movable member in operation, a linear increase in the distance of travel provides a substantially linear increase in fluid flow through the effective operational area of the at least one aperture.
• the interior chamber comprises a substantially cylindrical interior
• the movable member is a rotatable sleeve secured within the substantially cylindrical interior and having a substantially cylindrical outer wall
• the outlet aperture is provided to the substantially cylindrical outer wall
• the movement of the sleeve through the distance of travel comprises rotation about an axis.
• the movable member is a slidable plate member.
• the rate of change of the effective operational area increases according to an equation including at least one exponential factor, and more preferably according to a polynomial equation of at least a second degree.
• the polynomial equation is of a third degree or of a fourth degree.
• y is the rate of change of the effective operational open area
• x is the distance of travel of the movable member, expressed as a decimal ranging from a fully closed aperture position at 0.0, to a fully open aperture position at 1.0.
• the valve comprises a single aperture.
• such single aperture has a configuration which is substantially trilateral, and more preferably includes at least one curved side.
• the aperture configuration is defined by substantially linear first and second edges and a third edge connected to and having a curvature towards each of the first and second edges, and in this aspect preferably the first edge is substantially parallel to the axis and the second edge is substantially perpendicular to the first edge; more preferably the first edge and the second edge are of substantially equal length.
• the curvature is selected from partial parabolic, arcuate, and a curve defined by a plurality of mutually connected linear segments.
• the curvature is defined according to an equation including at least one exponential factor, preferably according to a polynomial equation of at least a third degree, more preferably of a fourth degree.
• y is the curvature
• x is the distance of travel of the movable member, expressed as a decimal ranging from a fully closed aperture position at 0.0, to a fully open aperture position at 1.0.
• the aperture configuration comprises a plurality of wall connection members defining a plurality of sub- apertures, preferably having a configuration selected from at least one of slots and perforations.
• the exterior wall of the valve body further comprises a vent operatively connectable to a source of ambient atmospheric air; and the movable member further comprises a movable member inlet operably alignable with the vent.
• a movable member inlet has a quadrilateral configuration, and where the movable member is a rotatable sleeve, preferably the movable member inlet has a trapezoidal configuration, wherein two parallel sides are oriented substantially parallel to the direction of rotation of the movable member.
• Figure 1 is an exploded view of a valve according to a first embodiment of the present invention
• Figure 2 is a schematic illustration of the assembled valve shown in Figure 1 indicating direction of fluid flow through the valve and the valve body outlet to the vacuum source;
• Figure 3 is a schematic illustration of the assembled valve shown in Figure 1 showing the direction of air flow from the valve body inlet to the suction device;
• Figures 4a to 4d show the progression of the valve body outlet opening as the valve sleeve is rotated by the actuator within the valve body, with Figure 4a showing the initial opening and Figure 4d showing the valve in near fully opened position;
• Figure 5 shows the valve body outlet in fully opened position with the attachment means to further piping removed;
• Figure 6 is a diagram showing the valve sleeve intended for use in the valve shown in Figures 1 to 5 including the inlet and outlet apertures;
• Figure 7 is a graph showing the percentage open area of a valve aperture according to a first embodiment of the invention, as a function of the valve sleeve position;
• Figure 8 is a graph showing the percentage open area of a valve aperture according to a second embodiment of the invention as a function of the valve sleeve position
• Figure 9 is a schematic diagram showing the position of the valve of the invention in a papermaking vacuum system
• Figure 10 shows a valve in a third embodiment of the invention
• Figure 11 shows the sliding member in the embodiment of Figure 10
• Figure 12 shows progressive steps in the adjustment of the valve in the embodiment of Figure 10;
• Figure 13 is a graph showing the percentage open area of a valve of the prior art in comparison to a valve aperture in an embodiment of the invention.
• Valve sleeve 105 is operationally secured to actuator 200 (see Figure 2), protectively located beneath valve cover 102, by drive flange 106, so that when valve cover 102 is secured over valve body 112, valve sleeve 105 is selectively rotatable within valve body 112, the rotation being controlled by actuator 200.
• the wall of sleeve 105 is provided with an outlet aperture 107, which is configured according to the invention, and located so as to be operationally brought into and out of alignment with the outlet at flange 110 and thereby connection with the vacuum source, allowing for a flow path in the direction of arrow 250 ( Figure 2).
• valve sleeve 105 shows valve 100 with flange 110 removed so that outlet aperture 107 is visible in the fully open position, similar to the position in Figure 4d.
• Figure 6 shows valve sleeve 105 including outlet aperture 107 and inlet aperture 108.
• valve bottom 115 When fully assembled, valve bottom 115 would be located above and proximate to flange 113. Opening 114 provides for operational connection of actuator 200 (Figure 2) to sleeve 105 via drive flange 106 ( Figure 1) to allow transmission of rotational force.
• this increasing rate of change is preferably determinable by a polynomial equation of at least the second degree. More particularly preferred features, including suitable polynomial equations and numeric values, are discussed above.
• valve sleeve 105 was installed in a valve body 112 as part of valve 100 substantially as shown in Figures 1 to 3 and vacuum applied through piping attached to flange 110 which passed through valve 100 to a papermaking process via further piping attached to flange connection 113. Rotation of valve sleeve 105 via drive assembly 200 produced a variance in vacuum pressure applied to the papermaking process that was substantially linear in accordance with the objectives of the invention.
• Figure 8 is a graph showing the relative change in the open area of the valve body outlet as a function of valve sleeve position according to a second embodiment of the invention.
• two sides of the trilateral aperture are curved and the apex of the trilateral aperture is oriented towards the direction of rotation of the valve sleeve.
• the open area will in this case be twice that of the portion shown above the x axis.
• the apertures of the invention can be of numerous shapes, not necessarily symmetrical, provided that they result in the appropriate increased rate of change of open area in relation to the distance of movement of the movable member.
• FIG. 9 shows valve 100 of the present invention as located in a typical papermaking vacuum system.
• the valve 100 is operably connected by outlet flange 110 to vacuum source 400, and by inlet flange 113 to an air/water separator device 402 and thus to the papermaking drainage unit 403.
• Vacuum pressure information is transmitted via line 404 to a vacuum sensor in valve 100 and vacuum control information is transmitted via shielded cordset line 405 to and from controller 406, which regulates actuator 200 ( Figure 2) in the valve 100, so as to rotate sleeve 105 ( Figure 2) and adjust vacuum pressure in the system according to need.
• Line 401 provides a by-pass in the event that vacuum control via valve 100 is not required, or when the valve must be removed for service.
• FIGS 10 to 12 show respectively a valve 360 according to a second embodiment of the invention provided with a movable valve member such as slide member 305 ( Figure 11), and three schematic illustrations of the valve in operation.
• a planar valve slide member 305 replaces the rotary sleeve member used in the embodiment of Figures 1 to 6.
• valve 360 comprises a valve body 312 provided with valve outlet 317 for connection to a vacuum source and valve inlet 318 for connection to the appropriate location in the equipment (not shown) in a papermaking process.
• Slide member 305 is operationally secured to actuator 300 so that slide member 305 can be selectively positioned within valve body 312.
• Slide member 305 is provided with inlet apertures 308a and 308b configured and located so as to be operationally brought into and out of alignment with a vent 311in valve body 312 on movement of the slide member 305 to selectively allow or restrict the passage of ambient air through the vent and into valve body 312.
• the slide member 305 is further provided with an outlet aperture 307 which is configured according to the invention so as to provide the required rate of change in open area and located so as to be operationally brought into and out of alignment with the valve outlet 317 and thereby connection with the vacuum source, allowing for a flow of negative pressure from the vacuum source.
• FIGS 12a to 12c show the progressive opening of outlet aperture 307 and corresponding closing of inlet apertures 308a and 308b as the slide member 305 is moved from a fully closed position in Figure 12a to a fully open position in Figure 12c.
• the locations of inlet apertures 308a and 308b, and outlet aperture 307, are spaced apart such that, upon sliding movement of slide member 305 to close inlet apertures 308a and 308b, and to open outlet aperture 307 to connect to the vacuum source (as shown in Figures 12a and 12b) the inlet apertures 308a and 308b are preferably completely closed before the opening of outlet aperture 307 commences.
• Figure 12a shows the valve body 312 of the vacuum valve 360 (see Figure 10) with the inlet apertures 308a, 308b in the fully open, or bleed, position, and the outlet aperture 307 in the fully closed position;
• Figure 12b shows the vacuum valve 360 with the outlet aperture 307 in a partially open position and the inlet apertures 308a, 308b in the fully closed position;
• Figure 12c shows the vacuum valve 360 with the outlet aperture 307 in the fully open position and the inlet apertures 308a, 308b in the fully closed position.
• outlet aperture 307 is presented as a trilateral aperture having two opposed curved sides.
• the shape of outlet aperture 307 is designed such that the open area presented to the valve outlet 317 at each position provides the desired rate of change in open area, as discussed further above, and as exemplified in Table 2.
• the shape of outlet aperture 307 may be generally triangular, such as is shown in Figures 5 and 6, or it may comprise a plurality of slots, drilled holes or other suitable perforations, in each case located in relation to each other in a manner such that they present the appropriate rate of change in open area, and thus provide the advantageous linear change in vacuum pressure as a function of opening or closing the valve.
• Figure 13 is a graph depicting the percentage open area of a valve according to the present invention, in comparison to a ball type prior art valve such as commonly used in a papermaking process.
• the percentage open area of the prior art valve is shown on the Y-axis as a function of valve position for various values along the X- axis, and identified by line C.
• the line identified as D provides corresponding information for a valve in an embodiment of the present invention.
• the open area C of the prior art valve changes substantially linearly with respect to changes in position between fully closed and fully open, going from approximately 5% open at position 0.1, to about 10% open at position 0.2, to about 20% fully open at position 0.3, up to 90% open at position 0.9.
• FIG 14 this is a graph providing a comparison between the rate of change in open area as a function of valve position for a prior art valve, and a valve in accordance with the present invention.
• the prior art valve of Figure 14 is of the same general type as the prior art valve identified by line C in Figure 13.
• the rate of change in open area for the prior art valve, between the fully closed and fully open positions, is identified by line E in Figure 14, and it can be seen that the rate of change increases significantly in the early stages starting from the fully closed position, slows significantly in the intermediate stages, and approaches a constant level in the later stages approaching the fully open position, i.e. as line E approaches the horizontal.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Sliding Valves (AREA)
• Details Of Valves (AREA)

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• 2011
  • 2011-04-29 PL PL11718866T patent/PL2564094T3/pl unknown
  • 2011-04-29 US US13/643,400 patent/US9404588B2/en active Active
  • 2011-04-29 WO PCT/US2011/034448 patent/WO2011137287A1/en active Application Filing
  • 2011-04-29 CN CN201180026661.6A patent/CN102947630B/zh active Active
  • 2011-04-29 EP EP11718866.4A patent/EP2564094B1/en active Active

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